基于定常吸气方式的大跨桥梁风致颤振抑制方法

以改善桥梁断面空气动力特性,提高大跨桥梁风致颤振稳定性为目的,提出了基于绕流控制原理的定常吸气方法。以我国虎门大桥为研究对象,采用基于计算流体动力学的数值方法模拟来流风与桥梁断面定常吸气共同作用下的桥梁断面绕流风场。采用Scanlan颤振分析方法分析了该桥梁在定常吸气作用下的颤振稳定性。计算结果表明,吸气作用使主流更加贴近壁面,降低了模型扭转运动下的气动扭矩,定常吸气提高了大跨桥梁的风致颤振稳定性。     

定常吸气改善桥梁断面风致静力特性的数值

目的 改善桥梁断面空气动力特性,提高桥梁抗风能力.方法 以某桥梁闭口扁平箱梁断面模型为研究对象,利用基于计算流体动力学的数值方法模拟来流风作用下桥梁断面的绕流风场,并计算桥梁断面静力3分力(阻力、升力、扭矩).结果 静力计算结果显示,与未采用吸气情况下相比,定常吸气后断面的升力与扭矩基本没有变化,而阻力却显著降低,且随着吸气能量的增加吸气减阻效果加大.结论 定常吸气可以有效地抑制风流过钝体断面而产生的分离,使主流更加贴近壁面,进而达到减少断面阻力的目的,定常吸气是桥梁断面减阻的有效手段.     

吸风管道的数学模型及其解法

吸风管道应用于设备的局部排风系统。文中给出了吸风管道的数学模型及其求解方法，最后给出了工程实例。     

气吸式排种器排种性能影响因素的试验研究

采用均匀设计的方法进行了气吸式排种器排种大豆质量影响因素的试验研究,考察了排种器排种盘转速和真空室压力与性能参数之间的关系,建立了粒距合格率、漏播率与重播率与影响因素之间的数学模型,获得了回归方程和最优结构参数。对于该气吸式排种器排种盘转速和真空室压力的最优化值分别为0.58r.s-1和0.003MPa,对气吸式排种器的设计具有指导意义。     

JZF浮选机工作原理

本文利用流体动力学的原理,结合试验研究,对JZF浮选机的槽体结构、叶轮结构、吸气原理,搅拌原理和矿浆运动轨迹作了初步分析,从理论上证实了该机结构的合理性和工作原理的先进性.     

局部排风系统的管道设计

介绍了局部排风管道系统的设计原理以及计算静压和剩余静压的计算方法，最后给出了根据设计原理求解管道直径的方法和工程实例。     

Robotic suction nozzle design optimization for severe accident portable air-cleaning system

A new portable filtered air-suction system (PoFASS) is proposed in this paper to prevent the release of radioactive fission products into the atmosphere from severe core meltdown accidents in nuclear power plants (NPPs), which has become very important after the Fukushima accident. The PoFASS consists of a robot arm with a vent line, a robot body equipped with a radioactive filter, and a robot suction nozzle that is the shape of a hand with fingers. By controlling the angle of the robot fingers on the robot suction nozzle, it can change its own shape to completely adapt to cover the damaged sections found in NPPs, and consequently, radioactive release to the atmosphere is effectively prevented. Surveying all the possible shapes of damaged sections in non-containment structures, six distinctive cases were identified. The minimum number of robot fingers that can cover all six cases of damaged sections was mathematically determined to be four, but in the design of the suction nozzle, six robot fingers were included to take into consideration the extension limit of the extensible cover of the suction nozzle as well as the area to be covered at the damaged sections. A complete mathematical model was developed to validate the covering capacity of the designed suction nozzle for all six cases. The minimum number of robot arm rods to access to any damaged section in NPPs was also determined to be three; hence, the PoFASS can access the hatch door of a containment buildings or the damaged sections of containment buildings, turbine buildings, and auxiliary buildings in NPPs. Experimental verification for the proposed PoFASS was successfully done with a prototype suction nozzle for the six cases of damaged sections.